// Formatting library for C++ - std::ostream support
//
// Copyright (c) 2012 - present, Victor Zverovich
// All rights reserved.
//
// For the license information refer to format.h.

#ifndef ABEL_STRINGS_INTERNAL_OSTREAM_H_
#define ABEL_STRINGS_INTERNAL_OSTREAM_H_

#include <ostream>

#include "abel/strings/internal/format.h"

FMT_BEGIN_NAMESPACE

template<typename Char>
class basic_printf_parse_context;

template<typename OutputIt, typename Char>
class basic_printf_context;

namespace detail {

template<class Char>
class formatbuf : public std::basic_streambuf<Char> {
  private:
    using int_type = typename std::basic_streambuf<Char>::int_type;
    using traits_type = typename std::basic_streambuf<Char>::traits_type;

    buffer<Char> &buffer_;

  public:
    formatbuf(buffer<Char> &buf) : buffer_(buf) {}

  protected:
    // The put-area is actually always empty. This makes the implementation
    // simpler and has the advantage that the streambuf and the buffer are always
    // in sync and sputc never writes into uninitialized memory. The obvious
    // disadvantage is that each call to sputc always results in a (virtual) call
    // to overflow. There is no disadvantage here for sputn since this always
    // results in a call to xsputn.

    int_type overflow(int_type ch = traits_type::eof()) override {
        if (!traits_type::eq_int_type(ch, traits_type::eof()))
            buffer_.push_back(static_cast<Char>(ch));
        return ch;
    }

    std::streamsize xsputn(const Char *s, std::streamsize count) override {
        buffer_.append(s, s + count);
        return count;
    }
};

template<typename Char>
struct test_stream : std::basic_ostream<Char> {
  private:
    // Hide all operator<< from std::basic_ostream<Char>.
    void_t<> operator<<(null<>);

    void_t<> operator<<(const Char *);

    template<typename T, FMT_ENABLE_IF(std::is_convertible<T, int>::value &&
                                               !std::is_enum<T>::value)>
    void_t<> operator<<(T);
};

// Checks if T has a user-defined operator<< (e.g. not a member of
// std::ostream).
template<typename T, typename Char>
class is_streamable {
  private:
    template<typename U>
    static bool_constant<!std::is_same<decltype(std::declval<test_stream<Char> &>()
            << std::declval<U>()),
            void_t<>>::value>
    test(int);

    template<typename>
    static std::false_type test(...);

    using result = decltype(test<T>(0));

  public:
    static const bool value = result::value;
};

// Write the content of buf to os.
template<typename Char>
void write_buffer(std::basic_ostream<Char> &os, buffer<Char> &buf) {
    const Char *buf_data = buf.data();
    using unsigned_streamsize = std::make_unsigned<std::streamsize>::type;
    unsigned_streamsize size = buf.size();
    unsigned_streamsize max_size = to_unsigned(max_value<std::streamsize>());
    do {
        unsigned_streamsize n = size <= max_size ? size : max_size;
        os.write(buf_data, static_cast<std::streamsize>(n));
        buf_data += n;
        size -= n;
    } while (size != 0);
}

template<typename Char, typename T>
void format_value(buffer<Char> &buf, const T &value,
                  locale_ref loc = locale_ref()) {
    formatbuf<Char> format_buf(buf);
    std::basic_ostream<Char> output(&format_buf);
#if !defined(FMT_STATIC_THOUSANDS_SEPARATOR)
    if (loc) output.imbue(loc.get<std::locale>());
#endif
    output << value;
    output.exceptions(std::ios_base::failbit | std::ios_base::badbit);
    buf.resize(buf.size());
}

// Formats an object of type T that has an overloaded ostream operator<<.
template<typename T, typename Char>
struct fallback_formatter<T, Char, enable_if_t<is_streamable<T, Char>::value>>
        : private formatter<basic_string_view<Char>, Char> {
    constexpr auto parse(basic_format_parse_context<Char> &ctx)
    -> decltype(ctx.begin()) {
        return formatter<basic_string_view<Char>, Char>::parse(ctx);
    }

    template<typename ParseCtx,
            FMT_ENABLE_IF(std::is_same<
                    ParseCtx, basic_printf_parse_context<Char>>
                                  ::value)>
    auto parse(ParseCtx &ctx) -> decltype(ctx.begin()) {
        return ctx.begin();
    }

    template<typename OutputIt>
    auto format(const T &value, basic_format_context<OutputIt, Char> &ctx)
    -> OutputIt {
        basic_memory_buffer<Char> buffer;
        format_value(buffer, value, ctx.locale());
        basic_string_view<Char> str(buffer.data(), buffer.size());
        return formatter<basic_string_view<Char>, Char>::format(str, ctx);
    }

    template<typename OutputIt>
    auto format(const T &value, basic_printf_context<OutputIt, Char> &ctx)
    -> OutputIt {
        basic_memory_buffer<Char> buffer;
        format_value(buffer, value, ctx.locale());
        return std::copy(buffer.begin(), buffer.end(), ctx.out());
    }
};
}  // namespace detail

template<typename Char>
void vprint(std::basic_ostream<Char> &os, basic_string_view<Char> format_str,
            basic_format_args<buffer_context<type_identity_t<Char>>

            > args) {
    basic_memory_buffer<Char> buffer;
    detail::vformat_to(buffer, format_str, args
    );
    detail::write_buffer(os, buffer
    );
}

/**
  \rst
  Prints formatted data to the stream *os*.

  **Example**::

    abel::print(cerr, "Don't {}!", "panic");
  \endrst
 */
template<typename S, typename... Args,
        typename Char = enable_if_t<detail::is_string<S>::value, char_t<S>>>
void print(std::basic_ostream<Char> &os, const S &format_str, Args &&... args) {
    vprint(os, to_string_view(format_str),
           detail::make_args_checked<Args...>(format_str, args...));
}
FMT_END_NAMESPACE

#endif  // ABEL_STRINGS_INTERNAL_OSTREAM_H_
